ETH builds first super-conducting quantum component from graphene

ETH researchers have for the first time produced a superconducting element from twisted graphene double layers, namely a SQUID (superconducting quantum interference device). In quantum technology, these sensitive sensors are used as quantum bits (qubits). These are fundamental elements that can be used to perform quantum operations and build more complex circuits.

According to a press release, this world first builds on the work of researchers from the group of Klaus Ensslin and Thomas Ihn at the Laboratory for Solid State Physics at ETH. About a year ago, they were able to demonstrate that what are known as Josephson junctions, the basic building blocks of superconducting devices, can be built with twisted graphene.

However, the researchers are not keen to describe their superconducting graphene SQUID as a breakthrough for SQUID technology. Because these graphene SQUIDs are no more sensitive than conventional SQUIDs made of aluminum and, like them, must also be cooled down to temperatures of less than 2 degrees above absolute zero. However, according to Ensslin, they noticeably expand the range of applications: “Five years ago, we were already able to show that graphene could be used to build single-electron transistors. Now we’ve added superconductivity”.

It is remarkable that depending on the voltage applied, graphene can be insulating, conducting or even superconducting. In addition, it is now possible to combine the transistor of a semiconductor and the SQUID of a superconductor in a single material. According to Ensslin, future research will focus on combining the benefits of two quantum systems by using graphene on the same crystal.